With the consistent growth of optical network-based communication techniques, different kinds of optical network services have continued to emerge, such as cloud computing, video on demand, wavelength leasing, optical layer virtual private networks (OVPN), and the like. While these novel network services bring convenience to people's lives, stricter demands regarding the reliability of these services are also being introduced. In order to increase the reliability of optical network services, backup routes are usually set in addition to the main routes in an optical network. When there is a problem with a main route in an optical network, the optical network services on the main route can be switched over to the backup route to maintain normal operation of those services.
In recent years, the concept of a shared risk link group (SRLG) has usually been employed when evaluating the reliability of the optical network. An SRLG represents a group of links that share a certain physical resource in an optical network, such as a group of links that share the same node or the same cable. When that physical resource is damaged, the group of links which share this physical resource will break down. For example, assuming a group of links is laid in the same cable, if that cable is damaged, those links in the group will simultaneously break down.
If both the main route and the backup route in the optical network are located in the same SRLG, then if a physical resource of that SRLG is damaged, there will be failures on both the main and backup routes at the same time. Hence, it is essential to detect the SRLGs in an optical network to make sure that the main route and the corresponding backup route are allocated to different SRLGs.
Conventional techniques for detecting SRLGs usually use an instrument having a polarization detecting function to detect polarization characteristics of optical links. In accordance, when the polarization characteristics of two optical links are the same, those two optical links will be considered to be in the same SRLG.
However, these conventional techniques all have problems. For instance, the polarization characteristic of an optical signal has a three-dimensional component. In applications, it is often difficult to test and analyze the three-dimensional component. Hence, it is difficult to implement a method based on judging whether links in the same group are in the same SRLG based on the polarization characteristics of the optical links. A new approach is required.